The first winter storm watches of 2020 have been hoisted for the Stateline! They take hold officially Friday Evening around dinnertime, and remain in effect through late Saturday Night or very early Sunday Morning. Given the most recent model trends, I fully expect these watches to be upgraded to warnings on Friday, perhaps as early as 3:00 Friday Morning.
Computer forecast model projections have become much more closely aligned with regard to the evolution of the incoming storm. There are to be two distinct waves of precipitation, one coming Friday Evening/Overnight, the second coming Saturday Afternoon/Evening.
We'll kick the storm off harmlessly enough with light rain late Friday Afternoon. As temperatures continue to cool, though, rain transition to freezing rain from northwest to southeast. Icing will likely begin in areas west and northwest of Rockford around dinnertime Friday. In the Rockford Metro, that changeover is to occur sometime between 8:00 and 9:00pm. Areas south and east of Rockford will see the changeover between 9:00 and 11:00pm.
Our Timecast Model continues to suggest a break in the action is to occur sometime around or shortly after Midnight. In reality, that may be a bit premature. It's more likely that any break in the action would hold off until closer to dawn Saturday, or perhaps even after that. We'll need to keep a close eye on upcoming high-resolution model runs to better time out when that break may occur. Before the first round of precipitation winds down, there could be a brief mix with some sleet or snow, especially north and west of Rockford, with some modest snow/sleet accumulations possible by Saturday Morning.
Most models suggest a period of quiet weather during the morning hours of Saturday, before the next round of precipitation begins. The second round is to come almost exclusively as snow for most of us. The exception to this rule may be in southeastern portions of the region, those along and south of I-88, where freezing rain may occur for the first few hours of the afternoon. Snow will continue areawide Saturday Evening before tapering to flurries and eventually ending altogether around or shortly after midnight.
Now, for the million dollar question... How much snow can we expect? In all honesty, it depends on where you live. Most of the Stateline can expect between 5 and 9 inches of snowfall. However, a few areas may pick up 10 or 11 inches, while others may only see 2 to 4 inches. The candidates most likely to pick up the heaviest amounts of snow will be in Southern Wisconsin, while the lightest snow amounts will be found across portions of Whiteside, Southern Ogle, Lee, and DeKalb Counties. Before folks living in those areas go celebrating, thinking they've avoided any severe impacts, there's this extremely important caveat. The areas that get the least amount of snow will be doing so because those areas will be getting the most amount of ice. The highest ice accumulations will be found in areas south and southeast of Rockford. With gusty winds likely through the duration of this event, power outages are likely to occur.
This is the time to prepare for the incoming storm. Any travel that needs to be done, any supplies that need to be purchased, and any errands that need to be run should be taken care of by Friday Afternoon. From Friday Evening through Saturday Night, travel is strongly discouraged. Travel should not be resumed until mid-morning Sunday, when crews will have had ample time to clear the roads.
We'll continue to keep close watch on any and all developments that unfold in the hours leading up to the storm's arrival, and will keep you abreast of any changes to the forecast that may occur.